Freshwater tank filling when hooked to city connection

Swyg · 05-11-2021, 11:39 AM

I think I may know what the answer
to this inquiry is...but.
Our freshwater tank is filling up...when hooked to city connection,
Assuming water pump is letting water thru.

Help!

**flybouy** · 05-11-2021, 12:09 PM

John? Got your Carnac hat handy?

Swyg, it would really be helpful if we knew the make and model number of your trailer.

bobbecky · 05-11-2021, 12:38 PM

Regardless of the trailer, most likely it is the built-in check valve in the pump that is leaking water backwards into the fresh water tank. You might try running a lot of water using the pump to see if there is debris that can be flushed through. If that doesn't work, you can disassemble the pump to physically clean the check valve. Replacement of the pump is also an option. I don't know why, but rarely or never do they install a screen ahead of the pump on new rigs, but that would help prevent the debris issue. When ours developed a leak, and we were nowhere close to an RV dealer, I just went to a local hardware store and bought a Sharkbite type check valve to cut in after the pump, which solved my problem. If you do that, do not install one on the tank side of the pump because the suction side fittings are usually not able to handle pressure. The photo shows the brass check valve I installed in our rig.

Swyg · 05-12-2021, 05:26 AM

2018 Keystone Laredo 5th wheel,
290SRL

**flybouy** · 05-12-2021, 05:51 AM

The purpose for asking the question is so that informed, not assumed advice can be given. There were units made that the water valve that you selct to fill the fresh water tank would leak past the O rings in the valve and constantly run water into the FW tank.

Swyg · 05-12-2021, 06:06 AM

Appreciate any thoughts and help!

**JRTJH** · 05-12-2021, 06:34 AM

No idea of what equipment "might be" in your trailer.

If you have a "convenience center with a valve to fill the fresh water tank" those valves have O-rings in the valves. When the valves are turned with pressure on them, there is a possibility (maybe a probability) to dislodge the O-rings causing them to leak, and then to "fill the fresh water tank" even when not desired...

If you do not have a "convenience center with that type valve" but rather have a single valve behind the city water connection, that "diverter valve" may be leaking which causes the same situation, the water tank filling when not desired...

If you have a "gravity fill system" (pour water into the tank through an opening on the side of the trailer) there is a "built in one way valve" in the water pump. That built in valve also provides water under pressure to the trailer. Occasionally, a piece of debris will be sucked into the pump (from the water tank) and can damage or dislodge the pump diaphragm, causing it to "leak back into the tank when connected to city water"....

As you can see, knowing what trailer, what pump, what water fill system you have is important to knowing how to recommend a solution.....

One of the above is "probably the type system you have" but how to get "detailed solutions" is an extremely long process of typing repair instructions, only to be told, "I don't have that kind of system"....

So, depending on what type of tank fill system you have will determine what you need to do to fix it.

Swyg · 05-12-2021, 06:47 AM

That gives me food for thought,
I have attached a photo of convenience center.

Big 417 · 05-12-2021, 08:32 AM

Yeah, your tank fill is on. Turn that 90°, problem solved

bobbecky · 05-12-2021, 09:54 AM

Actually, his normal/fill valve is in the correct, Normal, position. Turned down will put it into the fill position.

Swyg · 05-12-2021, 10:14 AM

I thought it was correct....labeling system is horrible.

Big 417 · 05-12-2021, 10:56 AM

Yup, terrible lol. You just get it figured for the season.....and then after storage it's all jibberish again lol

Swyg · 05-12-2021, 11:26 AM

Yep, that's it

Swyg · 05-12-2021, 11:30 AM

Thanks, greatly appreciated.
Live and learn!

Sarge2 · 05-12-2021, 11:37 AM

Quote:

Originally Posted by Swyg

I thought it was correct....labeling system is horrible.

Honestly I would have thought it was in the fill position also going by the little valve decal... it's a terrible labeling for sure...

Mamarino · 05-27-2021, 07:10 AM

Quote:

Originally Posted by Swyg

I think I may know what the answer
to this inquiry is...but.
Our freshwater tank is filling up...when hooked to city connection,
Assuming water pump is letting water thru.

Help!

Yes, that happened to me last year. The Manufacturer sent me out a new pump. Before I received the new pump the problem fixed itself. I believe that something was stuck leaving the valve open and then maybe with travel it dislodged itself. Been working ok since. Just keeping the new pump in case it happens again.

Bamabox · 05-27-2021, 07:39 AM

I had that happen once, and I think it was caused by switching from city to tank fill while under city pressure, then back to city. Just wanted to add a little to the tank. Made sure never to do that again, and it has not reoccurred. Was thinking maybe under pressure the valve didn’t close completely going to the tank.

Swyg · 05-27-2021, 08:39 AM

Thanks for the reply

roadglide · 05-27-2021, 09:07 AM

I have The convenient center to fill the tank and the outside fill cap after reading about plastic directional valve failure. I put a warning sign in my brain do not touch. I always use the outside manual fill port.

erm626 · 05-27-2021, 03:23 PM

Quote:

Originally Posted by bobbecky

Regardless of the trailer, most likely it is the built-in check valve in the pump that is leaking water backwards into the fresh water tank. You might try running a lot of water using the pump to see if there is debris that can be flushed through. If that doesn't work, you can disassemble the pump to physically clean the check valve. Replacement of the pump is also an option. I don't know why, but rarely or never do they install a screen ahead of the pump on new rigs, but that would help prevent the debris issue. When ours developed a leak, and we were nowhere close to an RV dealer, I just went to a local hardware store and bought a Sharkbite type check valve to cut in after the pump, which solved my problem. If you do that, do not install one on the tank side of the pump because the suction side fittings are usually not able to handle pressure. The photo shows the brass check valve I installed in our rig.

Wouldn't a ball valve work just as well instead of the check valve ? Just shut if off if not using the pump ?

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